Displaying roads using symbol level drawing
Many users often need to display road networks and want to represent their connectivity in term of overpasses, underpasses, bridges, and so forth. This would occur in any situation where road connectivity and navigation pathways need to be portrayed.
Here are the steps for a simple example:
- Symbolize your line features so that you have a different symbol for each combination of road types—for example, Interstate, State highways, Surface streets—and any desired multilayered symbols.
- Open the Symbol Levels dialog box for your feature layer or group layer and turn on symbol level drawing.
- Change the draw order of your symbols based on the order that you want your lines represented on the map. Symbols at the top of the list are drawn last.
- Set your Join and Merge settings.
In these categories, also define road elevation levels so that you can discern the drawing order for each. For example, if you have complicated interchanges, your list of levels might include Ground level (0), Ramp (1), Overpass (2), Second Overpass (3), and so on.
Generally, when symbolizing roads, you will want all road symbols to be joined to represent connected roads. However, only merge two symbols if you want them to appear to be connected on the map. For an overpass/underpass effect, specify no merge.
- If your data has complicated interchanges, it is useful to use attribute fields that indicate type, as well as fields that indicate the road level—for example, Ground (0), Ramp (1), Overpass (2), and so on. Use the Unique values, many fields renderer for symbolizing roads that are modeled this way. To learn more, see Drawing a layer using categories.
- If all your street data is stored in a single feature class, then you should set up unique values symbology for your feature layer and also enable symbol level drawing at this level. However, if your street data is stored in multiple feature classes, then you will have several feature layers in your map representing this data. Place these layers inside a group layer and enable symbol level drawing for it.
- Merge settings are chained up the list of symbols. Consider a list of four symbols. If the first symbol—from the bottom—is set to merge, it means that it is merged with the second symbol. If merge is also checked for the second symbol, it means that the first, second, and third symbols are all merged together. If the third symbol is not set to merge, then the chain stops at the third symbol.